Sunday, June 17, 2007

Why Flash Flood in KL?

Recently everyone is concern about the flash flood happened in Kuala Lumpur. Over this 2 weeks the weather in Klang Valley was very unusual and flash flood occurred in several places in KL in this 2 weeks.

Many people don't know why it happened and started to blame or point fingers to each other. I'm not surprise to see it, because everytime when anything wrong happened, everyone will started blame on each other. To me, I'll find out what is the main causes to lead on flash flood happened, it's no point for me to blame on others.

Here I just want share with you all my research and study on this situation for the past few years. Let's look at the geographical of Klang Valley, the major rivers are Klang River, Gombak River and Batu River. The other tributaries are Ampang River, Keroh River, Kerayong River, Kuyoh River, Damansara River, Penchala River and others.

We have two dams (Batu Dam and Klang Gates Dam) and few flood retention ponds but it's still not adequate to hold the rain water.

History of Major Floods

There are many major floods happened in Klang Valley since in 1920s. If you observe the frequent of floods, you can see the numbers of flood increasing in recent years.

From my record, the 1971 major flood was the worst ever in the history which happened almost whole Peninsular of Malaysia. It was believe the rainfall was 100 years return period, which is possible happen at least once in 100 years.

Let's look at some major flood pictures...

Causes of Floods

Rapid and Uncontrolled Development

Heavy Siltation

Reduction of River Capacity

River Constrictions

From 4 major causes, let me give some simple explains how it happens:

Look at the figure above, the land after development will become like 'water proof', the rain water will have no where to go through into the soil, so this phenomena will increase the surface water run off. If the drainage system are not design properly, the water run off will cause the flash flood happen.

Improper land development also will caused heavy siltation in drainage system, not only that, it also can caused land slide happened.

This is what happened on improper planning of a township, the heavy siltation in rivers will reduce the river capacity. It also destroyed the river ecosystem/diversity, this is why we hardly to see any living things like fish in the city's river.

Constrictions of river also another problem to create river water over flow from river. For example the picture above, the bridge was constructed lower than the flood level. That's why the bridge will block the water flow in the river and the back flow of water will spille out from the river.

Constrictions of structures also will disturbed the water flow during rainy days.

This is the very common situation we can see, illegal squatters and rubbish. I'm really sad that the mentality of Malaysian still treat our rivers as a rubbish dumping ground. I've seen on my own eyes a mamak shop in KL throw their rubbish directly into the river. Imagine if everyone does the same thing, our living place will become very sick.

Our river or drainage system is like artery in our body, once got any blockages, we will in trouble such as heart attack. Now, we are living in a 'heart decease' environment, it will burst anytime without any notice.

So, my conclusion is we have to blame on ourself for without the awareness of keeping our living place healthy. You can still blame on government of never did their job to clean it, but have you ever think that who did it in the first place?

The business mentality here also never concern about the environmental impact, they just never let go any empty land or reserved forest to develop the properties for their big profit only. If they follow all the EIA (Environmental Impact Assessments) studies and some proper guidelines, this will reduce the flash flood happened.

Good post. Truly informative. But apart from ppl throwing rubbish into the river and such, we still need to blame the gomen for poor town planning. Also, it's gomen's duty to educate the ppl no to throw rubbish into the river and impose strict rules to fine those who did it.

thanks, kenny. that really fills us in a lot, and shows that we shouldn't blindly blame on the government. ultimately, whatever government has done for us will be wasted if our third world mentality remains. we are all responsible for this.

However, I disagreed with you that we have to "blame on ourself for without the awareness of keeping our living place healthy" as the reasons of flood.

The unhygienic aspects and garbages will block the drains and to clog and thus overflow but will not cause such pandemic flood situation as experienced.

The fundamental is that: the fault lies with town planning and DID. DID was a party to all approvals of housing development and projects. There isn't a master plan that have looked into the needs and capacity of the discharges over a period of 20-years. All plans are approved based on "yesterdays" capacity. If you cared to do a survey in various housing development in the city, you can find that the roadside drains for 4-8 blocks of condominium is 12" dia and the pipe culverts are only 24" dia. and conveying over a distance of more than one kilometer to drain at the monsoon drain. Furthermore then monsoon drain are incapable to discharge at the required velocity. Example, is the river along Jalan Gurney, the river bank always overflowed when it rains for more than one hour (the capacity is just inadequate).

What is needed is a thorough study of the adequacy, capacity, and the long-term needs. It is estimated to cost some RM10bil to rectify. We have monies for everything except a proper drainage system. That's Vision 2057.

[purple~mushroom]Yes you were right? But have u think if our government is too strict also people complain, this thing all most work together.

[lp]I was the one did the presentation slide for my boss to present it.

[pisang goreng]Yes, but if u see who the one design? Not gov anymore, now days all design given out to private sectors to design

[poonky]Me too

[erinalaw]Thanks, glad that you were escape from the disaster.

[helen]You are welcome

[rabbit]Not that pro, just share experience only ma

[iwan]I always choose the place that can't flood then only stay.

[winn]Yalor...

[mott]Thanks, but I still not qualify as a cikgu la... haha

[sasha]Did many years ago lor...

[_butt]Glad you got the point, we all must work together.

[nonnie]Haha... I'm not only pro in rock ma.. :P

[maverick]For your information, DID not the only party who approve housing development, local council plays the major role. In my experience, they did rejected lots of housing development design, but with the political issue, they can't do anything, for example the Dataran Merdeka car park. DID is not an enforcer department.

Furthermore, DID and DBKL always have conflict in taking care of drainage system in KL. DID only responsible on major rivers and DBKL will responsible the rest. Monsoon drains, normal drains and tributaries (small rivers) are under DBKL.

I know you got more experience in this than me and know more than me, but what I want to point out is not to stand at government side. We must work out together.

Oh I got talk about rubbish that clog the drains, etc but urs is very detailed. I love this. Really can put some sense on the public, especially those few 'people' provided they understood english and know how to read

brilliantly written my friend. those pictures are really shocking, particularly the one on TTDI.

anyway, i have to agree with Maverick, we cant just look at ourselves and say we could have done something. yeah, in a way, we can... but how much a we do? if we all dont dispose garbage everywhere... it probably just free up some drains. but we will never be able to influence the development plan of scrupulous businessman...

based on your entry and what i see in the progression of our township... i am sure there will be more floods ahead. the smart tunnel will not solve the problems u mention.

Well, do you really think these people don't know the problem? But who wants to take up the responsibilities? To solve this, we need multi-agencies co-operation, and this is a impossible task in Malaysia.

helo kenny,tq so mch...teaching english language for the upper form rural sch n my topic for ths wk is caring for environment in particular finding the causes n effects for flash flood....ths is very helpful....didnt expect to gt such information n was only plan for them to read frm a newspaper cutting bt ths is better,i can introduce them the word 'blog'...tks a million.

Luckily nowadays have flood gate to prevent water entering buildings and basement car park. I have seen some of these floodgates installed around Kuala Lumpur city center and they are manufactured locally and looks very study and heavy. City skyline have change so much and not to mention the weather these days it will only get worse so I think we will have to get use to seeing more floodgates around.